Enzyme Quiz

What is a ribozyme?

• A type of protein with catalytic properties

• A type of RNA with catalytic properties

• A type of lipid with catalytic properties

• A type of carbohydrate with catalytic properties

Answer explanation

A ribozyme is a type of RNA that has catalytic properties, meaning it can facilitate biochemical reactions, similar to enzymes, which are typically proteins. This distinguishes it from proteins, lipids, and carbohydrates.

What is the main difference between simple enzymes and complex enzymes?

• Simple enzymes require cofactors, complex enzymes do not

• Simple enzymes are composed only of protein, complex enzymes include a small organic group

• Simple enzymes are inactive, complex enzymes are always active

• Simple enzymes are larger in size, complex enzymes are smaller

Answer explanation

The main difference is that simple enzymes are made only of protein, while complex enzymes consist of protein plus a small organic group, known as a cofactor, which is essential for their activity.

What is an apo-enzyme?

• The non-protein part of an enzyme

• The protein part of an enzyme without cofactors

• A metal ion required for enzyme activity

• An organic molecule derived from vitamins

Answer explanation

An apo-enzyme refers specifically to the protein part of an enzyme when it is not bound to its cofactors. This distinguishes it from the holoenzyme, which includes both the apo-enzyme and its cofactors.

What forms a holoenzyme?

• Apo-enzyme + cofactor

• Apo-enzyme + prosthetic group

• Cofactor + coenzyme

• Simple enzyme + complex enzyme

Answer explanation

A holoenzyme is formed when an apo-enzyme, which is the inactive form of an enzyme, combines with a cofactor, which can be a metal ion or a small organic molecule. This combination is essential for the enzyme's activity.

What is a prosthetic group in the context of enzymes?

• A loosely bound cofactor

• A coenzyme derived from vitamins

• A coenzyme or metal ion covalently bound to the enzyme

• A protein part of the enzyme

Answer explanation

A prosthetic group is a coenzyme or metal ion that is covalently bound to an enzyme, playing a crucial role in its activity. This distinguishes it from loosely bound cofactors or coenzymes derived from vitamins.

What suffix do the names of enzymes usually end with?

• -ose

• -ase

• -ine

• -ate

Answer explanation

Enzymes typically end with the suffix '-ase', which distinguishes them from other biological molecules. For example, lactase and amylase are both enzymes, while '-ose' is used for sugars, '-ine' for proteins, and '-ate' for salts.

Which type of enzyme is responsible for adding phosphate groups?

• Oxidases

• Kinases

• Dehydrogenases

• Proteases

Answer explanation

Kinases are enzymes that catalyze the transfer of phosphate groups to substrates, a process known as phosphorylation. This is crucial in regulating various cellular functions, distinguishing them from oxidases, dehydrogenases, and proteases.

What is the primary function of ribozymes as discovered by Thomas Cech?

• Breaking down proteins

• Catalysing covalent changes in RNA

• Splitting ATP

• Adding oxygen

Answer explanation

Ribozymes, as discovered by Thomas Cech, primarily function by catalyzing covalent changes in RNA, demonstrating that RNA can have enzymatic activity, contrary to the belief that only proteins serve as enzymes.

What type of reaction releases heat?

• Endothermic

• Exothermic

• Neutral

• Catalytic

Answer explanation

An exothermic reaction releases heat into the surroundings, making it feel warm. In contrast, endothermic reactions absorb heat, resulting in a cooling effect.

What is the term for the energy required to start a chemical reaction?

• Kinetic energy

• Potential energy

• Activation energy

• Thermal energy

Answer explanation

The energy required to initiate a chemical reaction is called activation energy. It is necessary to overcome the energy barrier for reactants to transform into products.